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Last class -

PVC. silicones. polycarbonate. aramid. Today –. epoxy. Last class -. Creep, relaxation, recovery . H 2 C-C-C{-O- -C- -O-} n C-C-CH 2. H. H. H. H-C-H. H-C-H. O. O. H. H. H. H 2 N-R-NH 2. hardener. epoxy. Prepregs. Some specific polymers . angular WC fragments.

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Last class -

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  1. PVC silicones polycarbonate aramid Today – epoxy Last class - Creep, relaxation, recovery

  2. H2C-C-C{-O- -C- -O-}nC-C-CH2 H H H H-C-H H-C-H O O H H H H2N-R-NH2 hardener epoxy Prepregs Some specific polymers

  3. angular WC fragments Co matrix phase Composites - overview Example - carbide tools (previously discussed)

  4. Composites - overview Artificial combination of matrix phase & dispersed phase Matrix: metal, alloy ceramic mat'l polymer Dispersed phase: particulate fiber

  5. Works like precipitation hardening Composites - metal matrix composites (MMCs) Particulates: ThO2-dispersed Ni (TD Ni) sintered Al powder (SAP) - except strengthening maintained at hi T Improves: strength creep resistance hi T corrosion resistance

  6. Matrix mat'ls Composites - metal matrix composites (MMCs) Fibers: Conts - C, SiC, B, Al2O3 Disconts - C, Al2O3 , SiC whiskers May get rxn betwn phases at hi T

  7. Matrix Composites - ceramic matrix composites (CMCs) Particulates, fibers: SiC, B, Al2O3 , C, SiC & Si3N4 whiskers Improve fracture toughness: slow crack growth deflect crack tips redistribute stresses around crack tips bridge crack tips

  8. Composites - polymer matrix composites (PMCs) Fibers: mainly - glass (GFRPs), carbon (CFRPs), aramid, others - B, SiC, Al2O3

  9. Composites - polymer matrix composites (PMCs) Matrix

  10. Composites - polymer matrix composites (PMCs) Very common - polyesters, vinyl esters

  11. Composites Role of matrix in FR composites: a. transfer stresses betwn fibers b. provide barrier to environment c. protect fibers Matrix/fiber bond: matrix must wet fiber physical & chemical bond desirable mechanical interlocking Fibers frequently coated w/ coupling agent

  12. non-coupled coupled Composites

  13. Composites Fibers - variables amount fiber length distribution orientation Fiber orientation can be random aligned intermediate

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